Sigma supersport running cool

[Chris Perry]

Dear All,

Once more I call upon the wisdom of blatchat for enlightenment.

Last year i had my Sigma 125 upgraded with caterham 140 Supersport cams and ECU. Since then it always seems to run cool.

Today i have replaced the thermostat and also the temperature sender near the coil pack for new parts from Caterham.

The thermostat has a bleed hole with ball bearing which was installed at 12 o'clock.

Alas, it is still running cool.

When stationary the fan comes on at about 80 degrees and the temperature gauge does not fluctuate.

But when on the move the temperature gauge can drop to about 50 degrees when i give it the beans and fluctuates with speed.

I have hunted for another temperature sender on the engine but can only find one.

Is a running temperature of 50 degrees something to be concerned about and do other 140 Supersports run at a similar temperature?

Do i need to consider blanking off some of the radiator?

Thanks in advance,

Regards,

Chris Perry

[Jonathan Kay]

What temperature do you want it to run at?

Are you sure that the thermostat works? Do you think a new one with a different temperature rating might have been fitted with the engine work?

Jonathan

PS: There have been quite a lot of reports of overcooling, but mostly on K engines IIRC. Blanking some of the radiator may be necessary.

[Jim 123]

I recall that the fan is meant to come in about 92 degrees.  This may be in the build manual. My Sigma tends to run at 80 when warm pretty constantly. 

[colindavies56]

i put  a 50mm strip of card along the bottom of the rad and it seems to keep it warm a bit better in the winter.just removed it for the summer.leave it ticking over in the garage for a while. remember its still cool out there.

[ChrisC]

My Sigma always ran cool according to the gauge.  However easymap and the ECU showed a much more normal reading, 90 and the fan kicked in at 100 (from memory).   So i just lived with the gauge underreading.   Maybe you can find someone local with easymap to confirm your engines running temps.

[DJ.]

I suspect Chris is correct, it's just the reading is wrong. The fan is coming on when stationary, and if the true temperature was only 50C, the thermostat would never open. The heat produced by the engine has to be going somewhere.